gRPC is a high-performance, open-source RPC (remote procedure call) framework that can be used to build microservices.

 It uses HTTP/2 for transport and Protocol Buffers as the interface description language. 

https://grpc.io/

Stands for Remote Procedure Call (RPC) with Google’s Protocol Buffers

Uses binary data for communication instead of HTTP

Supports streaming data for real-time updates

Uses protocol buffers for serialization, which can be more efficient than JSON or XML

Can be used across different programming languages

Designed for high-performance, low-latency communication between microservices

Requires more setup and configuration than REST, and may require more expertise to use effectively

Can be less interoperable than REST or GraphQL, since it is not based on HTTP

Here is also a nice table which highlight the difference between REST, GraphQL, and REST, you can use it for quick revision: